Astronomers have discovered a planet drifting through space, not orbiting a star. Such cosmic wanderers are believed to be common in the universe. But the new-found planet's proximity to our solar system - just 100 light years, or 1000 trillion kilometers, away - and the absence of any nearby stars have allowed the international [Canadian and European] team to study the planet's properties in greater detail than ever before.
Because it seems to be traveling with a group of about 30 young stars, researchers were able to determine it was the same age - between 50 and 120 million years old. Then, using computer models of planet evolution, they report it has a temperature of about 400 degrees Celsius, and a mass four to seven times that of Jupiter.
These free-floating objects can help astronomers understand more about how planets and stars form and behave. Rogue planets may have coalesced from the same dust and debris as normal planets before being ejected from their solar systems, or they may be brown dwarfs - stars that never grew large enough to trigger the reaction that causes starlight.
Lead researcher, Philippe Delorme of the University of Grenoble, said "If this little object is a planet that has been ejected from its native system, it conjures up the striking image of orphaned worlds, drifting in the emptiness of space."